Instrument display apparatus

ABSTRACT

An instrument display apparatus for use in combination with a substantially transparent panel including an instrument to be displayed positioned adjacent to the transparent panel and which is adapted to reflect ambient light onto the substantially transparent panel, and an artificial lighting assembly which is adapted to selectively supply light to the instrument whereby a reflection of the instrument may be viewed in the windscreen regardless of level of ambient natural light.

This patent application is a continuation-in-part of U.S. patentapplication Ser. No. 07/408,692 filed on Sep. 18, 1989 which is acontinuation-in-part of U.S. patent application Ser. No. 07/310,644, nowU.S. Pat. No. 5,005,009, which is a continuation-in-part of U.S. patentapplication Ser. No. 07/156,122, filed Feb. 16, 1988, now abandoned.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an instrument display apparatus andmore particularly to such a device which is adapted to produce areflected image of an instrument in a windscreen or other similarassembly such that an operator may view same while simultaneouslyviewing out through the windscreen.

2. Description of the Prior Art

The development of a "HEADS-UP" display and which hereinafter will bereferred to as HUD, had its genesis in the military aircraft field. Asshould be understood, in the operation of high speed aircraft such asfixed wing and rotary wing attack aircraft which are designed forcombat, it is extremely hazardous for the pilot or a crew member such asa weapons officer to momentarily divert their attention from a hostiletarget or other point of interest in the immediate vicinity of theaircraft to read the dials, gauges, instruments, warning indicators,etc. on the assorted instrument panels and other displays positioned invarious locations in the cockpit area but normally positioned below theaverage line of sight of the observer.

Those skilled in the art have long recognized that a HUD would be quiteuseful in such dangerous sports as high-speed motor car racing and couldperhaps be helpful in the day-to-day driving activities of averagemotorists.

In operation, a HUD allows an operator of a conveyance such as allmanner of overland vehicles, boats, aircraft, motorcycles, etc. to viewsubstantially within their line of sight, critical instrumentationdisplays, such as speed, fuel consumption, oil pressure, etc. withoutsubstantially diverting their vision and attention from an areaimmediately in front of the vehicle. Further, such devices may beutilized in other applications such as in ticket booths, bank tellerwindows, etc.

The prior art is replete with several examples of HUDs which aredesigned for specific purposes and applications. Examples of prior artHUDs and related assemblies are shown in several U.S. patents,particularly Steward U.S. Pat. No. 4,652,870: Banbury U.S. Pat. No.4,560,233: Spooner U.S. Pat. No. 4,347,508: and Garner U.S. Pat. No.4,453,163, to name but a few.

While it is speculated that the utilization of a HUD could conceivablyimprove the safe operation of a motor vehicle, the prior art deviceshave not been widely embraced for such an application. This has beendue, in large measure, to the physical size and complexity of theseprior art devices and their related assemblies. Further, commercialembodiments of HUDs installed in recently manufactured motor vehicleshave revealed numerous inherent shortcomings which have detracted fromtheir usefulness.

For example, one major drawback of the most recently manufactured HUDsis that the purchase price for same is usually cost prohibitive for mostpurchasers. Further, these devices do not operate effectively in manycommonly encountered operational environments. By way of illustration,the commercially available HUDs individually employ digital, vacuumfluorescent displays, the light of which is reflected in an adjacentwindscreen and which may be viewed by an operator. In one of thecommercial embodiments, a windscreen viewing enhancement device islocated somewhat out of the line of sight of the operator and which isadapted to reflect the light emitted by the display. Further, the othercommercial embodiment employs, in combination with the digital vacuumfluorescent display, several optically precise mirrors whichindividually manipulate the light generated by the display in apredetermined fashion and projects it onto the adjacent windscreen.While these devices operate with some degree of success, they becomeinoperable in extremely bright light, or are difficult to read when thevehicle moves from a brightly lit environment into a shaded area.

Still another problem encountered with the prior art HUDs which havebeen designed for use in motor vehicles is the propensity for suchdevices to exhibit a characteristic inability to cooperate with otherassemblies which are mounted in the area of the dashboard. Further, andwith respect to one of the commercially available HUDs, the operator'seyes must be positioned within a very narrow cone of vision. If theoperator moves his head outside of this cone, he will not be able to seethe display. In addition, the prior art devices are not aestheticallyappealing and therefore detract from the stylish appearance of thevehicle upon which it is installed.

Therefore, it has long been known that it would be desirable to have aninstrument display apparatus which could be employed in all manner ofoverland vehicles, watercraft or aircraft, which could be manufacturedand purchased at a relatively nominal cost, which is both highlyefficient in operation and capable of operating in environments havingvarious ambient light levels for the purpose of displaying an instrumentface on an adjacent windscreen and within the line of vision of theoperator, and which reduces to an absolute minimum the assorted problemsinherent with the related prior art devices adapted to perform theidentical function.

OBJECTS AND SUMMARY OF THE INVENTION

It is therefore an object of the present invention to provide animproved instrument display apparatus.

Another object of the present invention is to provide such an apparatuswhich can be directly controlled, either manually, or automatically,under all types of ambient lighting conditions to provide an image whichis clear and distinct.

Another object of the present invention is to provide an apparatus whichmay be manufactured as an integral component of a vehicle or whichfurther can be manufactured in the manner of a retrofit.

Another object of the present invention is to provide such an apparatuswhich fits easily into existing vehicle dashboard designs.

Another object of the present invention is to provide an apparatus whichabsorbs or otherwise substantially blocks light waves which wouldotherwise create an undesirable optical effect.

Another object of the present invention is to provide an apparatuswherein the display face emits light waves in a peak frequency rangewhich is substantially attenuated by the windscreen.

Another object of the present invention is to provide an apparatus whichoperates in combination with windscreens having various angularinclinations, and which further is not rendered inoperable by externalinterference such as bright sunlight, the bright lights of oncomingvehicles, or other conditions which may drastically alter the ambientbackground lighting environment.

Another object of the present invention is to provide an apparatus whichis characterized by ease of installation, simplicity of construction,and which further can be sold at a relatively nominal price whencompared with related prior art devices.

Another object of the present invention is to provide an apparatus whichis easily accessible for maintenance, modification or the like.

Another object of the present invention is to provide an apparatus whichis operable to obtain the individual benefits to be derived from relatedprior art devices while avoiding the detriments individually associatedtherewith.

Further objects and advantages are to provide improved elements andarrangements thereof in an instrument display apparatus for the purposesdescribed which is dependable, economical, durable, and fully effectivein accomplishing its intended purposes.

These and other objects and advantages are achieved in an instrumentdisplay apparatus for use in combination with a substantiallytransparent panel and wherein in the preferred embodiment the apparatusincludes an instrument to be displayed positioned adjacent to thetransparent panel and having a display face including a first portionwhich is translucent and light reflective and a second portionsurrounding the first portion and which provides contrast for the firstportion, and wherein the first portion is adapted to reflect ambientlight onto the substantially transparent panel; and means forselectively supplying light to the first portion whereby the firstportion may be viewed in the substantially transparent panel regardlessof the level of ambient light.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a fragmentary, longitudinal, side elevation view of anoperator's position of a vehicle employing the first form of theapparatus of the subject invention.

FIG. 2 is a rear elevation view of an operator's position of a vehicleemploying the first and second forms of the apparatus of the presentinvention.

FIGS. 3A-3C are a schematic, longitudinal, sectional view of severalwindscreens having predetermined tint fields of various characteristics,and taken from a position along line 3--3 of FIG. 1 and FIG. 12,respectively.

FIG. 4 is a somewhat enlarged, longitudinal, sectional view of awindscreen taken from a position along line 3--3 of FIG. 1 and FIG. 12and illustrating the optical effect which creates a "ghost" of a primaryreflected image.

FIG. 5 is a plan view of the first and second forms of the apparatus ofthe subject invention taken from a position along line 5--5 of FIG. 1and FIG. 12, respectively.

FIG. 6 is a graphic depiction of the light wave transmission andabsorbing features of a windscreen employing a tint field in accordancewith the teachings of the present invention.

FIG. 7 is a schematic diagram of a first electronic circuit employed inconnection with the present invention.

FIG. 8 is a schematic diagram of a second electronic circuit employed inconnection with the present invention.

FIG. 9 is a fragmentary, longitudinal, side elevation view of anindicator needle of the present invention.

FIG. 10 is an exploded view of a reverse printed character of thepresent invention and showing various layers of the character.

FIG. 11 is a schematic diagram of a third electronic circuit employed inconnection with the present invention.

FIG. 12 is a fragmentary, longitudinal, side elevation view of anoperator's position of a vehicle employing the second form of theapparatus of the subject invention.

FIG. 13 is a perspective, somewhat enlarged, exploded side elevationview of a housing utilized in connection with the second form of theinvention.

FIG. 14 is a perspective, somewhat enlarged, exploded side elevationview of an alternative housing utilized in connection with the secondform of the invention.

FIG. 15 is a fragmentary, perspective, exploded view of the second formof the apparatus of the present invention.

FIG. 16 is a somewhat enlarged top plan view of the lamp support plateof the second form of the present invention.

FIG. 17 is a somewhat enlarged bottom plan view of the lamp supportplate of the second form of the present invention.

FIG. 18 is a schematic diagram of a fourth electronic circuit employedin connection with the present invention.

FIG. 19 is a schematic diagram of a fifth electronic circuit employed inconnection with the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT First Form

Referring more particularly to the drawings, the first form of theapparatus embodying the principles of the present invention isdesignated generally by the numeral 10 in FIG. 1. As depicted therein,the apparatus is shown mounted in a vehicle 11 and which includes anoperator's compartment or position 12. The operator's position has aseat 13 for an operator 14. The vehicle includes a console or dashboard15 which has a top surface 20 and which is defined by a peripheral edge21. The peripheral edge of the dashboard includes a leading peripheraledge 22 and a trailing peripheral edge 23. Further, the vehicle includesa steering wheel 24, and a windscreen 25 is borne by the vehicle and ismounted adjacent to and in angulated, spaced relationship with thedashboard 15.

The windscreen 25 is defined by top and bottom peripheral edges 30 and31, respectively, and further includes an outside surface 32 and anopposite, inside surface 33. The windshield is of traditional designthat is, it may be manufactured of glass, plastic, polycarbonate,acrylic, crystal or mineral, or any other rigid transparent material. Asillustrated herein, the windscreen is a piece of safety glass havingfirst and second laminate portions 34 and 35, respectively, and whichare bonded together, and which include a synthetic polymer sheet 40which is sandwiched between the first and second laminate portions. Asearlier discussed, the present invention can be utilized in all mannerof overland vehicles, aircraft and water borne conveyances. Further,such devices may also be utilized in connection with bank teller'swindows, control areas, ticket selling booths, and other similarenvironments where a transparent panel is positioned between an operatoror observer and an object of interest which must be observed.

As best understood by reference to FIGS. 2 and 3 the apparatus of thesubject invention includes a predetermined tint field 41 which is borneby the windscreen and which is positioned substantially within the lineof sight of the operator 14 who is positioned in the operator's position12. The predetermined tint field, as illustrated, may include adiscreetly dimensioned area as shown in FIGS. 1, 2, and 12 or mayinclude the entire surface area of the windscreen 25. As best understoodby a study of FIG. 3, the tint field 41 may be created by a number ofdifferent materials or substances, including all manner of differentpolymers, glass, mineral or other coatings. The coatings may furtherinclude metallic additives which may be applied in molten form,solution, rolling adhesive or other means of attachment either directlyto the inside surface 33 of the windscreen 25 or made integral with thesynthetic polymer sheet 40 which is sandwiched between the first andsecond laminate portions 34 and 35, respectively, of the windscreen 25.As illustrated most clearly in FIG. 3, the predetermined tint field 41is shown, in Example A, as including a synthetic polymer sheet 42 whichis secured to the inside surface 33 of the windscreen 25. An acceptablesynthetic polymer sheet is commercially available and may be purchasedunder the brand name "LLumar window film." The film is manufactured byMartin Processing Inc. Further, and as shown in Example B of FIG. 3, thepredetermined tint field is made integral, as by a coating 43, or thelike, with the synthetic polymer sheet 40 which is sandwiched betweenthe first and second laminate portions 34 and 35. Additionally, and asbest seen in Example C of FIG. 3, the predetermined tint field may becreated by a dispersion of particulate matter, or other substances,which are made integral with the second laminate portion of thewindscreen and which define the predetermined tint field.

The predetermined tint field 41 imparts to the windscreen 25 improvedspectral and other optical characteristics which improve the quality ofthe reflected image which is produced by the apparatus 10. Moreparticularly, the tint field has a color which is adapted substantiallyto absorb or attenuate the frequency of light reflected or emitted bythe display face. The display will be discussed in the paragraphs whichfollow. Further, the tint field is operable to eliminate orsubstantially reduce an undesirable optical effect which willhereinafter be discussed as a secondary or "ghost" image and furtherimproves the intensity and color contrast relative to the ambientbackground illumination without violating standards for visible lighttransmission through the windscreen as mandated by the requirements oflaw. The optical effect which creates ghost images and the diminution ofits overall deleterious effects on the operation of the presentinvention will be discussed in greater detail in the paragraphs whichfollow.

As best illustrated by reference to FIG. 1, an aperture of predetermineddimensions 50, is formed in the console 15 and is adapted to receive asupporting frame or housing 51 which encloses and surmounts an analogspeedometer instrument display and which is generally indicated by thenumeral 52. The analog display 52 has a top surface 53, an oppositebottom surface 54 and an aperture 55 of predetermined dimensions isformed therein. As best illustrated by reference to FIG. 5, the topsurface 53 of the analog display 52, includes a display face having aplurality of reverse printed, translucent characters which areindividually indicated by the numeral 60. Further, a pair of directionalsignalling characters, and an engine malfunction character, 61 and 62respectively are displayed thereon. As should be understood, thedirectional signalling characters as well as the engine malfunctioncharacter are translucent. However, they further include a "dead front"which substantially inhibits them from reflecting ambient natural lightwhich comes in through the windscreen. The significance of this featurewill be hereinafter discussed in greater detail. Further, the remainderof the display face surrounding the translucent characters has a flatblack color which provides a high contrast background for thetranslucent characters. It should be understood that the display face,in certain applications, may be manufactured in a manner wherein theindividual reverse printed characters 60 are printed in a fashionwherein they are opaque and nonreflective, and the remainder of thedisplay face is rendered translucent and reflective. In this fashion thetranslucent, bright background provides high contrast for the darknonreflective characters.

The translucent characters 60 are positioned in a predetermined patternas best illustrated by reference to FIG. 5. As should be understood, theinventor has discovered that by adjusting the size of the characters theapparent effect of the secondary or "ghost image" can be minimizedthereby making the reflected image quite readable. In this regard, theinventor has discovered that as the size of the characters increase thevisual impact or effect of the ghost image decreases and similarly, asthe focal length increases, that is, the distance from the operator 14to the windscreen 25, the apparent effect of the ghost image decreases.In practice, the inventor has found it useful to form the characters ina manner wherein they have respective overall length dimensions whichare approximately 10 mm and width dimensions, for the lines forming thecharacters, of approximately 2.7-3 mm.

As best illustrated by reference to FIG. 10, an analog display 52 isshown in an exploded fashion and which illustrates in greatlyexaggerated dimensions the various layers of paint or ink 60A which areutilized in preparing such an analog display on a polycarbonatesubstrate 60B which has an approximate thickness of 0.060 inch. Layersof flat black paint or ink 60C and white paint or ink 60D are applied tothe bottom surface thereof. As illustrated, the flat black paintprevents "light leakage" from below. Further and on top of thepolycarbonate substrate the following layers are applied in sequence.Layer 60E includes paint or ink which emits light in the frequency oflight selected. This is utilized for the characters 60, for example. Inaddition, a diffuser layer 60F, and a translucent red/orange layer 60Gare utilized for the directional signaling characters and the enginemalfunction character 61 and 62, respectively. A dead front layer 60H isapplied and is adapted to inhibit reflection of light off of thedirectional signaling characters and the engine malfunction character.Another layer of flat black paint or ink 60I is applied and whichprovides contrast for the characters. Finally, an antiscratch, hard,clear, synthetic coat 60J is applied to complete the process.

A movable indicator needle 63 is rotatably mounted on the analog display52 by a coiled spring return meter movement 64 which is fixed on thebottom surface 54 of the analog display by using suitable fasteners oradhesive (not shown). The coiled spring return meter movement is ofconventional design and therefore, for the sake of brevity, is notdiscussed in further detail herein. However, it should be understoodthat the coiled spring return meter movement is operable selectively toposition the indicator needle in predetermined locations along theanalog display 52 thereby indicating the overland speed of the vehicle.The coiled spring return meter movement is adapted to rotatably move theindicator needle in a counterclockwise direction, that is, in adirection whereby its reflected image appears to move in a properdirection when viewed from the operators position 12. This direction ofmovement is generally opposite to the traditional direction of movementof an indicator needle. This counterclockwise rotation is achieved bymeans of an electronic circuit which selectively delivers predeterminedamounts of voltage to the coiled spring return meter movement whichvaries linearly and inversely relative to the vehicle speed. Theoperation of three embodiments of this electronic circuit will bediscussed in greater detail hereinafter. Alternatively, the coiledspring return meter movement may be mechanically modified such that itwill operate in an appropriate fashion, that is, drive the indicatorneedle in a counterclockwise direction by utilizing an electroniccircuit which will be discussed in greater detail hereinafter. Thecoiled spring return meter movement is mechanically modified byreversing the position of the spring and modifying other subassemblies.Further, a device such as a stepping motor may be utilized to performthe identical function.

As best illustrated by reference to FIG. 9, the indicator needle 63which is utilized in both the first and second forms of the inventionincludes a substantially cylindrically shaped and vertically disposedbarrel 65 which is manufactured from a suitable light transmittingacrylic material. The main barrel is attached to the coiled spring metermovement 64 at attachment point 66 such that it rotates simultaneouslywith the meter movement 64. The barrel 65 mounts an acrylic pointerassembly 67 which extends radially outwardly relative to the barrel andwhich is adapted to receive light discharged from a light manifold andwhich is reflected in the barrel and down the pointer assembly. Thelight manifold will be discussed in the paragraphs which follow. Thepointer assembly has a bottom surface 68 which is angulated such thatlight reflected down the pointer assembly is reflected off of thissurface and towards the windscreen 25. The bottom surface is coated withmaterial which reflects light which lies in a peak frequency band whichis attenuated by the tint field 41. Similarly, the bottom surface isadapted to receive and reflect ambient natural light 110 which comes inthrough the windscreen 25. A black cover 68 is borne by the barrel 65 inthe manner shown in FIG. 9.

A dust cover 69 is borne by the housing and includes a substantiallyflat, transparent panel of coated and/or tempered glass, or othersimilar substances and which is adapted to prevent dust, moisture, etc.from interfering with the coiled spring return meter movement. The dustcover, and more particularly, the coating includes a high efficiencyanti-reflection coating (HEA) which is produced by Optical CoatingLaboratories, Inc. of Santa Rosa, Calif., and which is adapted toincrease the clarity of the glass and minimizes reflections. Thisreduces the impact of glare upon the operator 14. Another means by whichproblems related to glare can be addressed is by using technique called"geometric avoidance." This process includes analyzing the vehicle insuch a manner as to identify possible glare paths and thereafterdesigning a dust cover with two or possibly three critical dimensionswhich, when optimally placed, inhibits any glare from reaching theoperators eyes.

An auxiliary lighting assembly, and which is generally indicated by thenumeral 70, is borne by the vehicle 11 and includes a light manifold 71.The light manifold is made up of a plurality of Polymethyl Methacrylatebundles having fluorinated polymer cladding. A suitable optical fiber 72is manufactured by Mitsubishi Rayon under the "Eska" brand name. Each ofthe optical fibers 72 has an input end 73 and an opposite output end 74which is fixed to the bottom surface 54 by utilizing a suitable adhesivesuch as an epoxy or other resin, or which is ultrasonically welded, spinwelded or molded such that it is properly fixed to or disposed inadjacent spaced relation to the back surface of the display face. Theoutput ends 74 are positioned in light emitting relation relative to theindividual translucent characters 60, the directional signalingcharacters and engine malfunction characters 61 and 62, respectively,and the barrel 65. The input ends 73 of the individual optical fibersare positioned in substantially light receiving relation relative to ahigh intensity light source 75. This high intensity light source 75 mayinclude a Tungsten halogen lamp such as that manufactured by the GeneralElectric Company under the brand name "Precise" MR-16 VNSP TungstenHalogen Lamp. The lamp includes a reflector 76 which focuses the lighton the input ends of the optical fibers. Further, the apparatus may beconstructed in such a fashion wherein a light manifold is not utilizedand a light source is merely positioned in light transmitting relationrelative to the bottom surface 54. This type of construction will bediscussed in greater detail with respect to the second form of theinvention. In addition, a shutter assembly, not shown, may be mounted onthe output ends of the optical fibers 72 which deliver light to thesignaling characters and engine malfunction character respectivelythereby preventing these characters from appearing in the windscreenexcept under signaling conditions. A shutter assembly as just describedcould also be mounted on the bottom surface 54 in the event theapparatus 10 does not utilize a light manifold.

An electronic circuit for selectively activating the auxiliary lightingassembly 70 is generally indicated by the numeral 79. A switchingassembly 80 is borne by the dashboard 15 and further is connected to asource of 12 volt power 81 which is produced by the vehicle 11. Theswitching assembly 80 includes a ground 82, and a pair of electricalconductors 83 electrically connect the ground and the source of 12 voltpower 81 with a 5K ohm variable resistor or potentiometer 84. A manuallyactuatable switch 85 selectively is movable by utilizing a wheel-likeassembly, not shown, from an open to a closed position. A pair ofelectrical leads 90 electrically connect the switch 85 and the 5K ohmpotentiometer 84 to a voltage regulator 91. The voltage regulator 91 ismanufactured by Motorola under the trade designation "LM350" and whichis commercially available through retail electronic shops. The voltageregulator 91 includes terminals which are labeled "input", "Adj" and"output", 92, 93 and 94 respectively. A photosensor 95, a fixed resistor100 having a value of 270 ohms, a capacitor 101 having a value ofsubstantially 54 microfarads and a ground 102 are electrically connectedtogether by an electrical conductor 103. An electrical conductor 104electrically connects the output 94 and the high intensity Halogen lightsource 75 with the ground 102.

As earlier discussed, the tint field 41 is operable to eliminate orsubstantially reduce an undesirable optical effect which has been termeda secondary or "ghost image". The ghost image has the effect ofproducing a double-image which blurs or clutters the primary reflectedimage such that the primary image is difficult to view. By way ofillustration, and as best seen by reference to FIG. 4, incoming rays ofnatural light 110 are shown as passing through the windscreen 25 andbeing reflected off of the top surface 53 of the analog display 52. Thereflected light, which travels along a first path 111, passes throughthe predetermined tint field 41 and a portion of this reflected light isthen reflected off of the inside surface 33. These reflected light wavesform the primary reflection which appears in the tint field, thereflected light waves travelling along a second path 112 towards theobserver 14. Those nonreflected light waves continue to pass through thesecond laminate portion 35 of the windscreen 25 and along a third path113. The nonreflected light waves travel along the third path 113 untilthey are reflected off of the outside surface 32 of the windscreen 25and travel along a fourth path 114 back towards the observer 14 tocreate the ghost image. However, the tint field acts upon the lighttraveling along the fourth path such that these light waves are absorbedor attenuated such that any ghost image is barely perceptible. Inaddition to the foregoing, federal law mandates that windscreens bedesigned to transmit at least 70% of the visible light spectrum. Inorder to comply with the provisions of law, the tint field has beendesigned to substantially and selectively attenuate or absorb only thosewavelengths of light reflected or emitted by the analog display 52. Moreparticularly, it has been discovered that upon achieving the selectivetransmission or reflection of light in predetermined frequencies, thetint field can be adapted to attenuate just those frequencies which liein a peak frequency band such that the average visible spectrumtransmission of the windshield is not reduced below the 70% requirementas mandated by federal law. In the present invention, the applicantshave selected a color for the reverse printed translucent characters 60which reflects or emits light waves which reside predominantly in a peakfrequency band of 625 through 700 nanometers. In accordance with theseteachings, the tint field 41 is adapted to absorb a high percentage oflight produced in this particular peak band without excessively reducingthe visible spectrum transmission average. While the windscreen 25transmission in the 625 through 700 nanometer band is less than 50%, thevisible spectrum average transmission is over 70%, which permits thewindscreen to meet federal standards. By way of example, and moreparticularly by reference to FIG. 6, a graphic illustration 120 shows aline 121 which indicates windscreen light transmission as compared withthe wavelength of the light for a windscreen utilizing a tint field 41which is adapted to attenuate light in the 625 to 700 nanometer band.Further, the display face reflectance is indicated by the line labeled122. This graphic illustration shows that an overall 70% lighttransmission requirement can be achieved by such selective attenuation.

It has been discovered that the substantial matching of the peakreflected frequencies of light produced by the translucent characters 60to the minimum light transmission characteristics of the tint field 41presents a three-fold benefit. The primary benefit is directed toreducing substantially the intensity of the secondary or ghost image.This effect is achieved because the light passing through the windscreen25 and which causes the ghost image passes through the tint field 41 ontwo occasions. On each occasion, the ghost image is weakened to such anextent that it becomes barely perceptible in relative comparison to theprimary image by the time it emerges in the operator's 14 line of sight.Further, and in addition to the foregoing, a secondary benefit of thetint field is to increase the image's contrast relative to the ambientbackground light by reducing the amount of in-band light, which isreadily apparent in the background. In the present instance, theinventors have selected a color for the translucent characters 60, whichlies in the red-orange band. However, this same concept can be appliedto virtually any color band such that the reflected image may appearyellow, green, blue, orange or pure red. As should be understood, thepresent color was selected because of its contrast with those colorswhich are quite common in the immediate environment. A third benefit isachieved because the tint field 41 creates a point of interest which theoperator 14 may look to when receiving information produced by theanalog display 52.

It should be understood that the individual characters 60 operate asdiffuse reflectors and which further are operable to transmit lightreceived from the individual acrylic optical fibers and direct sametowards the windscreen 25. In the preferred embodiment and as earlierdiscussed, the analog display 52 is manufactured from approximate 0.060inch thick polycarbonate 60B which has applied thereto paint or inkwhich will act in the manner as heretofore disclosed. The selection ofan appropriate paint or ink will normally include an analysis utilizinga spectragraph to determine the frequency of light reflected andthereafter an appropriate tint will be selected which will substantiallyattenuate the frequencies of light reflected. In practice, the thicknessof the paint deposited on the polycarbonate will depend upon variousfactors including the light intensity as delivered by the light manifoldas well as the application involved. However, it will be recognized thatan increase in reflectivity of a character 60 will cause a decrease inits ability to transmit light received from an optical cable. In thepresent invention, the inventors have found it advisable to print theindividual characters in the manner which is shown in FIG. 10 and whichwas discussed earlier.

A first embodiment of an electronic circuit 130 for controlling thecoiled spring return meter movement 64 is operable to actuate the metermovement 64 to rotatably move the indicator needle 63 in acounterclockwise direction such that the reflection of the indicatorneedle appears to move in a proper direction when viewed from theoperators position 12. By way of introduction, it should be understoodthat vehicle 11 is operable to produce an electronic pulse 131 whichindicates the overland speed of the vehicle. The inventors have, forexperimentation, utilized the electronic pulsed signals transmitted to adigital speedometer display which was installed on a 1989 CutlassSupreme automobile. The electronic circuit 130 includes a multiplicityof electrical conductors 132. The vehicle 11 also includes a source of12 volt power 133 which may be supplied by the vehicle's battery (notshown). The source of 12 volt power is supplied to a voltage regulator134, which will hereinafter be referred to as a 7805 semiconductor chip(7805 IC) and which is commercially available through retail electronicstores nationwide. The 7805 IC 134 has an input 135, and an electricalconductor 136 electrically connects the source of 12 volt power with the7805 IC. Further, the 7805 IC is operable to produce a substantiallyconstant 5 volt output 137 which is supplied to the electronic circuit130, as will hereinafter be described in further detail. The ground forthe above-identified electronic circuit 130 is generally indicated bythe numeral 140. The electronic circuit 130 includes a signal processormeans which is indicated by the numeral 141 and which may be purchasedin retail electronic outlets nationwide as a 555 integrated chip (555IC), which is used as a monostable. The 555 IC 141 is adapted to processthe electrical pulses 131 which are received from the vehicle 11 andproduce substantially uniform electrical pulses having a magnitude oramplitude of not greater than 5 volts and a predetermined durationperiod. The 555 IC receives 5 volts of power from the 7805 IC. The 555IC further includes a plurality of pins which are connected to theelectrical conductors 132. These pins include a V+ pin 142, a thresholdpin 143, a trigger pin 144, a DIS pin 145, an output pin 146, a resetpin 147, and a V/C pin 148.

A 5M ohm resistor 150 is electrically connected with the 555 IC 141.Further, a 1500 pF capacitor 151 and a 0.01 microfarad capacitor 152 areelectrically connected to the 555 IC 141. A 3.9K ohm resistor 153 iselectrically connected between the ground 140 and the electronic circuit130. Further, first and second resistors having values of 10M ohm areserially connected to the electronic circuit 130 and are designated bythe numerals 154 and 155, respectively. The electronic circuit 130further includes first and second resistors 160 and 161 having values of1500 pF and an operational amplifier 162, which is commerciallyavailable and designated as a 3130 integrated chip (3130 IC) and whichis adapted to receive the processed signals produced by the 555 IC 141.The 3130 IC further operators as a two pole low band pass filter. The3130 IC is commercially available through retail electrical supplystores nationwide. Electrically connected to the operational amplifier(3130 IC) is a 100K ohm potentiometer or variable resistor 163. The 100kohm variable resistor 163 is adapted to set the maximum output voltagefor the operational amplifier 162 which in the case of the analogspeedometer display 52 is approximately 1.4 volts. The 100k ohmpotentiometer comprises one portion of a calibration means whereby thecoil spring return meter movement 64 is operable to move the indicatorneedle 63 to selective locations along the display face 52, and whichcorrectly indicates the overland speed of the vehicle 11. The electroniccircuit 130 includes a capacitor 164 having a value of 47 pF and aresistor having a value of 100K ohms 165. In addition, a 47 pF capacitor170 is electrically connected to a second 100K ohm potentiometer orvariable resistor 171. The second potentiometer constitutes a secondportion of the calibration means which is adapted to set the minimumvoltage output for the operational amplifier 162. In the present case,the minimum voltage lies in a range of approximately 0-0.3 volts. Theoperational amplifier includes inputs which are generally designated bythe numeral 172 and an output 173. As should be understood, theelectronic circuit 130 is adapted to receive and process the electricalpulses 131 produced by the vehicle 11 into a source of voltage foractuating the coil spring return meter movement 64 which varies linearlyand inversely relative to the rate of electronic pulsing. Therefore, asthe speed of the vehicle increases, the voltage output of theoperational amplifier decreases. Conversely, when the vehicle speeddecreases the voltage output increases, thereby causing the coiledspring return meter movement to move the needle in a proper directionwhen it is viewed in reflection from the operator's position. As earlierdiscussed, the coil spring return meter movement may be mechanicallyaltered to achieve the desired affect. An electronic circuit foractuating a mechanically modified coiled spring return meter movementwill be described in greater detail hereinafter and in connection withthe second form of the invention. Further, no modifications may benecessary in certain applications.

A second embodiment of an electronic circuit 180 for controlling thecoiled spring return meter movement 64 is also operable to actuate thecoiled spring return meter movement 64 such that it rotatably moves theindicator needle 63 in a counterclockwise direction such that thereflection of the indicator needle appearing in the windscreen appearsto move in a proper direction when viewed from the operators position12. The electronic circuit 180 includes in addition to severalelectronic components which were earlier discussed, a plurality ofelectrical conductors 181. Further, the electronic circuit 180 receivesthe electronic pulses 131, which indicates the overland speed of thevehicle 11 at a location in the vehicle 11 that is designated as A9. Theelectronic circuit receives a source of 12 volt power 133 throughelectrical conductor 90 and which is supplied by the vehicle's battery(not shown), and which may be accessed in the vehicle at a locationwhich is designated A4. The source of 12 volt power is supplied to thevoltage regulator 134 and which was described earlier as a 7805semiconductor chip (7805 IC) and which is commercially available throughretail electronic stores nationwide. As earlier discussed, the 7805 ICsupplies a substantially constant 5 volt output 137 which is supplied tothe electronic circuit 180. The ground for the above-identifiedelectronic circuit 180 is generally indicated by the numeral 140. Theelectronic circuit 180 includes a 0.01 microfarad capacitor 182 which iselectrically joined to the source of electrical pulses produced by thevehicle A9 (131). Further, the electronic circuit 180 includes a 10K ohmresistor 183 and a pair of diodes 184 which are electrically connectedtogether to form a differentiator or signal modifier means 185 which isadapted to modify the vehicle electrical pulses in a manner to formelectrical pulses having a predetermined wave form and amplitude. Asshown herein, the electrical pulses produced by the signal modifiermeans 185 have an amplitude of not greater than 5 volts.

The electronic circuit 180 further includes a 100K ohm resistor 190 anda 0.1 microfarad capacitor 191 which are electrically connected to the555 IC monostable 141 in the manner as best shown by reference to FIG.11. Further, the electronic circuit 181 includes a 3.3K ohm resistor192. The electronic circuit has a 100K ohm resistor 193 and a 2.2microfarad capacitor 194 which comprise an integrator means which isgenerally indicated by the numeral 195, and which is adapted to receivethe electrical pulses which have been processed by the 555 IC 141, andwhich forms an integrated voltage output. The electronic circuit 180 ofthe present invention includes a quad operational amplifier which isgenerally indicated by the numeral 196, and which is commerciallyavailable through retail electronic stores nationwide under the tradedesignation "LM324". In the present invention, the electronic circuit180 utilizes only two of the four operational amplifiers available andtherefore for simplicity, only those operational amplifiers are shown.The quad operational amplifier 196 includes a first operationalamplifier which is generally indicated by the numeral 200 and whichincludes first, second, third and fourth pins 201 through 204,respectively. Pin 11 of the first operational amplifier is indicated bythe number 205. As best illustrated by reference to FIG. 11, the firstoperational amplifier is electrically connected with the integratormeans 195 and with the electrical power source 133 which is borne by thevehicle 11. Further, the first operational amplifier is adapted toproduce a voltage output at pin 201 which is substantially linearlyrelated to the pulse rate of the vehicle 11. A 100K ohm resistor 211 iselectrically connected between the first operational amplifier and thesecond operational amplifier 212. The second operational amplifier 212includes pins 12, 13 and 14 and which are designated by the numerals213, 214 and 215, respectively. As best illustrated by reference to FIG.11, the input for the second operational amplifier 214 is electricallyconnected with the output 201 of the first operational amplifier and theoutput 215 of the second operational amplifier is electrically connectedto the return meter movement 64. The electronic circuit 180 includesmeans for calibrating the voltage output of the second operationalamplifier. In the embodiment shown in FIG. 11, the calibration meansincludes first and second variable resistors 210 and 220, respectively,and which have individual resistance values of 100K ohms each. As shouldbe understood, the first variable resistor 210 is operable to controlthe maximum voltage output for the second operational amplifier and thesecond variable resistor is adapted to control the minimum voltageoutput of the second operational amplifier. The maximum and minimumvoltages were discussed earlier with respect to the first electroniccircuit 130. The second electronic circuit 180 additionally includes theelectrical circuit which was heretofore identified by the numeral 79 andwhich is adapted to selectively activate the Halogen lamp 75 in themanner which was previously described.

Second Form

The second form of the instrument display apparatus of the subjectinvention is generally indicated by the numeral 300 in FIG. 12. Asillustrated therein, the apparatus is shown mounted on a vehicle 11 andwhich includes the operator's compartment or position 12. The operator'sposition has a seat 13 for an operator 14. The vehicle includes aconsole or dashboard 15 which has a top surface 20 and which is definedby a peripheral edge 21. The peripheral edge of the dashboard includes aleading peripheral edge 22 and a trailing peripheral edge 23. Further,the vehicle includes a steering wheel 24, and a windscreen 25 is borneby the vehicle and is mounted adjacent to, and in an angulated, spacedrelationship with, the dashboard 15. The construction of the windscreenand the operation of the predetermined tint field 41 is substantiallyidentical to that which was earlier discussed with respect to the firstform of the invention and, therefore, are not discussed in furtherdetail herein. The second form of the invention includes a housing 301which is best illustrated by reference to FIG. 13 or in the alternative,a housing 302 which is shown in FIG. 14. The housing is mounted on orotherwise made integral with the dashboard using conventional fasteningor manufacturing techniques. Each of the housings 301 or 302 has a mainbody 303 which may be manufactured out of assorted materials includingvarious lightweight metals as well as synthetic polymers and othersubstances which may be extruded, stamped or otherwise molded into thedesired shape by employing conventional manufacturing methods. The mainbody of each of the housings includes three sidewalls 304 and a frontwall 305 which are respectively joined together or otherwise madeintegral to form a structure or container having a substantiallyrectangular shape. An opening 306 of predetermined dimensions is formedin one of the sidewalls and is adapted to provide a point of accesswhich permits electric leads (not shown) to enter the housing.Alternatively the opening may be formed in the front wall, or in bottomsurface 307. The housings further have a bottom surface 307 which isfixed to or made integral with the walls 304 and 305. The main bodies303 of each of the housings have an outside surface 310 and an opposite,inside surface 311 as well as a top peripheral edge 312 and a bottomperipheral edge 313. As best illustrated by references to FIG. 13 andFIG. 14, the housings include a circumscribing flange 314 which isdisposed in a substantially normal attitude relative to the outsidesurface 310 and which rests on or adjacent to the dashboard 15 when thehousing is installed. Further an opening 315 is formed in front wall 305and which permits an opaque cover to move from a stored position to alocation wherein it covers the individual housings. The opaque cover andits operation will be discussed in greater detail in the paragraphswhich follow.

As best seen by references to FIG. 13 and FIG. 14, a cover housing, andwhich is generally indicated by the numeral 320, is adapted to be fixedto the individual housings 301 and 302, respectively. The cover housingis individually operable to slidably receive an opaque cover which willbe discussed in greater detail hereinafter. As best understood byreference to FIG. 12, the cover housing 320 is mounted in a positionunderneath the top surface 20 of the dashboard 15. The cover housing hasa main body 321 which includes a top surface 322, a bottom surface 323,and a pair of sidewalls 324 join the top and bottom surface together andposition them in predetermined spaced relationship one to the other. Thecover housing may be manufactured as a separate subassembly, orotherwise molded or formed by conventional techniques as an integralunit. Further the cover housing may be made integral with the individualhousings. As best illustrated by reference to FIG. 13 and 14, a portion325 of the sidewalls 324 extends outwardly from the main body 321 andthereby provides a point of attachment for the cover housing to theindividual housings 301 and 302, respectively. Further, the coverhousing includes an end wall which is generally indicated by the numeral326.

As best seen by reference to the drawings, the inside surface 311 of thehousing 301 includes a plurality of grooves or channels 330 which aresubstantially continuous about the inside surface, and which are adaptedto support various components which will be discussed in greater detailhereinafter. The various grooves or channels 330 define five (5)discreet levels which will be referred to as a first, second, third,fourth and fifth level, 331 through 335, respectively. Further, thebottom surface 307 defines a sixth level 336. In the case of the secondhousing 302, it should be understood that the main body 303 has adiminishing outside dimension which defines a plurality of steps 340which individually form five levels which are designated by the numerals341 through 345, respectively. Further, the bottom surface 307 forms asixth level 346.

As best illustrated by reference to the exploded view of FIG. 15, thecoiled spring return meter movement 64 is adapted to be mounted on thebottom surface 307 by using suitable fasteners or an adhesive (notshown). As earlier discussed, the coiled spring return meter movement isof substantially conventional design, and is operable under normaloperating conditions to rotate the indicator needle 63 in asubstantially clockwise direction. However a conventional coiled springreturn meter movement may be rendered operable by utilizing theelectronic circuit 180 for example, to move the indicator needle in acounterclockwise direction such that upon viewing the indicator needlein reflection it appears to move in a proper clockwise direction.Alternatively, a reverse coiled spring meter movement may be utilizedand which is adapted to rotate the indicator needle 63 in asubstantially counterclockwise direction. As earlier discussed withrespect to the first form of the invention, electronic circuits 130 and180 are provided and which are adapted to provide a voltage output to aconventional coiled spring return meter movement which varies linearlyand inversely relative to the overland speed of the vehicle 11. Further,and as will be discussed in greater detail hereinafter, anotherelectronic circuit is provided which produces a voltage output for thereverse coiled spring meter movement 64 which varies linearly relativeto the overland speed of the vehicle. In any case, the electroniccircuits are adapted to cause the individual coiled spring return metermovements to move the indicator needle 63 in a proper direction suchthat the reflection of same appears to move in an appropriate directionwhen viewed in reflection in the windscreen.

The coiled spring return meter movement 64 is mounted on the sixth level336 and 346, respectively, and extends substantially normally andupwardly therefrom. Installed and supported on the fifth level 335 and345, respectively, is a lamp support plate and which is generallyindicated by the numeral 350. The lamp support plate may be manufacturedout of assorted flexible and synthetic materials, however, and in thepreferred embodiment described herein, the lamp support plate has a mainbody 351 which is adapted to receive suitable copper based etching whichwill be discussed in greater detail hereinafter. The main body 351 has asubstantially rectangular shape and which is defined by a peripheraledge 352. The peripheral edge has a top portion 353, and an opposite,bottom portion 354. Further, the lamp support plate has a top surface355, which is best seen by reference to the top plan view shown in FIG.16, and an opposite, bottom surface 356 which is best illustrated byreference to FIG. 17. A reflective coating may be applied to the topsurface. Further, the main body includes a major horizontal component360 and a substantially vertically disposed component 361 which extendssubstantially normally, upwardly, relative to the top surface 355 frombottom portion 354 of the peripheral edge 352. As best illustrated byreference to FIG. 16, the main body 351 of the lamp support plate 350has a substantially centrally disposed aperture 362 formed therein whichpermits the coiled spring return meter movement 64 to extendtherethrough. In an alternative form of the invention, not shown, an aircore gauge or meter movement may be substituted in place of the coiledspring return meter movement and mounted on the top surface 55. The aircore gauge would work in the same manner as the coiled spring returnmeter movement 64. Further, and formed in a predetermined pattern aroundthe centrally disposed aperture 362 is a plurality of light bulbapertures 363 which have a shape which permits them to individuallyreceive replaceable automotive light bulbs 364 which are of conventionaldesign. The light bulbs 364 are readily available from commercialsources. Examples of acceptable light bulbs are manufactured by GeneralElectric under the tradename "T 2-1/4 882 auto instrument halogen lightwith a printed circuit socket base, and T 3-1/4 PC 194 auto instrumentindicator light with printed circuit socket base". The light bulbs havea design which is familiar to those skilled in the art. The light bulbsare releasably fixed to and positioned in electrical contact with thelamp support plate by being slidably received in the individualapertures and thereafter rotated in a clockwise direction. The clockwiserotation positions the individual light bulbs in current receivingrelation relative to the lamp support plate. Further, and as best seenby reference to FIG. 17, the vertical component 361 includes a pair ofapertures 363 which are adapted to receive light bulbs 364. As should beunderstood the various light bulbs are positioned in attitudessubstantially in registry with or in light transmitting relationrelative to various reverse printed translucent characters 60 which areprinted on the display panel. Further, it should be understood that thelight bulbs 364 which are mounted on the vertical component 361 areadapted to provide light for illuminating the indicator needle 63. Thisrelationship is best imagined by a study of FIG. 9 wherein in the firstform of the invention, light is delivered to the indicator needle by theoptical cables or fibers 71. An aperture 364A is formed in the lampsupport plate and permits the coiled spring return meter movement 64 toextend therethrough.

As best understood by a study of FIG. 17, the bottom surface 356 hasaffixed thereto by etching or other suitable bonding, or manufacturingtechnique a conductive pathway 366 which includes a first pathway 371and a second pathway 372. Alternatively the conductive pathway may belocated on the top and bottom surface in particular applications. Asshould be understood, the first pathway is provided with electricalpower from an electronic circuit which will be discussed in greaterdetail in the paragraphs which follow and the second pathway provides aground. As should be evident by a study of FIG. 17, and when theindividual light bulbs 364 are twisted into an appropriate positionwherein they are disposed in electrical contact with the 50 canilluminate the individual light bulbs 364. The electronic circuit whichselectively activates the individual light bulbs 364 will be discussedin greater detail hereinafter.

Mounted in spaced relationship relative to the lamp support plate 350and at the fourth level 334 and 344 is a barrier plate which isgenerally indicated by a numeral 380. The barrier plate is manufacturedfrom a transparent substance such as glass, polycarbonate or othersimilar materials. The barrier plate 380 provides an insulating meansfor blocking the heat generated by the individual light bulbs 364. Thebarrier plate 380 includes a main body 381 which is defined by aperipheral edge 382 that is supported by the individual housings 301, or302. Further, an aperture 383 is formed in a predetermined position inthe main body and permits the coiled spring return meter movement 64 toextend therethrough. This relationship is seen most clearly by referenceto FIG. 15. The analog display face 52 is mounted in spaced relationshiprelative to the barrier plate and at the third level 33 or 343. Theanalog display face was discussed in significant detail earlier. In thepresent form of the invention a reflective coating may be applied to thebottom surface of the display face and which is adapted, in combinationwith a reflective coating applied to the top surface 355 of the lampsupport plate to provide a means for reflecting light onto theindividual translucent characters 60. Mounted in spaced relationshiprelative to the analog display face 52 and at the second level 332 or342 is the dust cover or glass panel 69. This also was discussedearlier. As best illustrated by reference to FIG. 15 an opaque cover 384is slidably mounted on the first level 331 or 341 and has affixedthereto a knob or handle 385 which may be grasped by the operator 14.The opaque cover is moveable along a substantially horizontally disposedpath of travel from a first position wherein it is located in the coverhousing 320, to a second position wherein it completely covers thedisplay face 52 thereby preventing sunlight from impacting upon orreaching same. The opaque cover permits the operator 14 to deactivatethe HEADS-UP device when desired. Further, the opaque cover provides ameans by which the deleterious effects of heat generated by sunlightimpacting on the instrument display may be dissipated or minimized whenthe automobile 11 is parked for prolonged periods of time in directsunlight.

An electronic circuit 400 for controlling the movement of a reversedcoiled spring return meter movement 64 such that it rotatably moves theindicator needle 63 in a proper direction such that the reflection ofthe indicator needle appearing in the windscreen appears to move in anappropriate direction when viewed in reflection from the operator'sposition 12 is best seen by reference to FIG. 18. The electronic circuit400 includes a plurality of electrical conductors 401. The electroniccircuit 400 receives the electronic pulses 131 which indicates theoverland speed of the vehicle 11 at a location in the vehicle that isdesignated as A9. Further, the electronic circuit receives a source of12 volt power 133 through the electrical conductors 401 and which issupplied by the vehicle's battery, not shown, and which may be accessedin the vehicle at a location which is designated A4 (133). The source of12 volt power is supplied to an adjustable voltage regulator 402 which,in the preferred embodiment, is an LM317 semiconductor chip or itsequivalent and which is commercially available through retail electronicstores nationwide. It should be understood that the LM317 is adjusted toprovide a substantially constant 10 volt output 403 which is supplied tothe electronic circuit 400. The voltage regulator 402 includes an input404 and further is electrically connected with a 3.3K ohm resistor 405and a 470 ohm resistor 406, the values of the resistors 405 and 406determine the voltage output value 403 of the voltage regulator 402. Theelectronic circuit 400 includes a 0.01 microfarad capacitor 182 which isconductively joined to the source of electrical pulses produced by thevehicle A9 [131]. Further, the electronic circuit 400 includes a 10K ohmresistor 183 and a pair of diodes 184 which are electrically connectedtogether to form a differentiator or signal modifier means 185 which isadapted to modify the vehicle electrical pulses in a manner to formelectrical pulses having a predetermined wave form and amplitude. Asshown herein, the electrical pulses produced by the signal modifiermeans 185 has an amplitude of not greater than the voltage outputproduced by the voltage regulator 402. In this embodiment the voltageoutput is adjusted to approximately 10 volts.

The electronic circuit 400 includes a 100K ohm resistor 190 and a 0.1microfarad capacitor 191 which are electrically connected to a 555 ICmonostable 141 in the manner as best shown by reference to FIG. 18.Further, the electronic circuit 401 includes a 3.3K ohm resistor 192.The electronic circuit has a 100K ohm resistor 193 and a 2.2 microfaradcapacitor 194 which comprise an integrator means and which is generallyindicated by the numeral 195, and which is adapted to receive theelectrical pulses which are produced by the 555 IC 141, and which formsan integrated voltage output. The electronic circuit 400 of the presentinvention includes a quad operational amplifier which is generallyindicated by the numeral 410 and which is commercially available throughretail electronic stores nationwide under the trade designation "LM324"or its equivalent. Alternatively a semiconductor chip having a singleoperational amplifier may be employed. In the present electroniccircuit, the electronic circuit 400 utilizes only one of the fouroperational amplifiers available and, therefore, for simplicity, onlythe single operational amplifier is shown. The operational amplifier 410includes first, second, third and fourth pins 411 through 414,respectively. Pin 11 of the operational amplifier is designated by thenumeral 415. As best illustrated by reference to FIG. 18, theoperational amplifier 410 is electrically connected with the integratormeans 195 and with the source of power produced by the voltage regulator402. Further, the operational amplifier is adapted to produce a voltageoutput at Pin 411 which is substantially linearly related to the pulserate of the vehicle 11. In the embodiment shown in FIG. 18, thecalibration means includes a variable resistor having a 100K ohmresistance value. As should be understood, the variable resistor isoperable to control the gain of the operational amplifier and itsmaximum voltage output for the operational amplifier 410 (approximately7.5 volts) thereby rendering a MOSFET transistor 421 capable ofcontrolling the reverse coiled spring meter movement 64 which positionsthe indicator needle 63 in a predetermined position on the display faceto properly indicate the overland speed of the vehicle 11. As best seenby reference to FIG. 18, an "N" type MOSFET transistor 421 provides acurrent controller means which is electrically coupled to the output ofthe operational amplifier 410. The current controller means 421 is alsoelectrically coupled with the reverse coiled spring meter movement 64and provides same with a maximum voltage of 3.7 volts. However it shouldbe understood that different meter movements may have different voltagerequirements and therefore the calibration means are provided. A 470Kohm resistor 422 is electrically coupled with the MOSFET transistor 421in the manner as best illustrated by reference to the drawings.

A second electronic circuit for selectively activating the light bulbs364 is generally indicated by the numeral 430. The electronic circuit430 includes a voltage regulator 91 which was described earlier as anLM350 and which is commercially available nationwide. The LM350 iselectrically coupled with a 10K ohm variable resistor 431 which is ofthe wheel type and which may be manipulated by the operator 14.Electrically coupled to the LM350 is a 57 microfarad capacitor 432 and a1K ohm resistor 435. Further, a 470 ohm resistor 434 and a photoresistor95 are electrically coupled to the LM350 and a switch 436 is positionedbetween the input 92 and the source of 12 volt power 133. In thisfashion, the switch 436 permits the light control circuit 430 to bedeactivated under appropriate environmental circumstances. Thiselectronic circuit provides the same advantages as described earlierwith regards to the electronic circuit 79.

As best illustrated by reference to FIG. 19, a third electronic circuit450 is employed in connection with the present invention and which isadapted to actuate the coiled spring return meter movement 64 in amanner wherein it moves the indicator needle 63 in an appropriatedirection when viewed from the operator's position. As should beunderstood, there are substantial similarities between the electroniccircuit 180 shown in FIG. 11 and that shown in FIG. 19. For purposes ofbrevity, therefore, only those features which distinguish the twocircuits are discussed in detail herein. The third electronic circuit450 includes a voltage regulator 402 which was described in detail withrespect to the electronic circuit 400. Further, the light controlcircuit 430 which was described earlier is identical in this embodimentof the invention. However, it should be noted that in comparison withthe electronic circuit 180 shown in FIG. 11, the first operationalamplifier 200 receives power from the voltage regulator 402 as opposedto the source of 12 volt power 133 as shown in FIG. 11. Further, thevariable resistor 210 is electrically coupled with the voltage output403 of the voltage regulator 402 as opposed to the source of 12 voltpower 133 as shown in FIG. 11. The electronic circuit 450 furtherutilizes a current controller means 421 which includes a MOSFET "N" typetransistor which is coupled with a 470 ohm resistor 422. In the samefashion as that previously discussed with respect to the electroniccircuit 180 shown in FIG. 11, the electronic circuit 450 is operable toactuate the coiled spring return meter movement 64 to move the indicatorneedle 63 in a counterclockwise direction such that it appears to movein an appropriate direction when viewed in reflection from theoperator's position.

OPERATION First and Second Form

The operation of the described embodiments of the present invention isbelieved to be readily apparent and is briefly summarized at this point.The instrument display apparatus 10 and 300 for use in combination witha substantially transparent panel or windscreen 25, is best illustratedby reference to FIG. 1 and 12. As shown therein, the analog instrumentdisplay 52 is borne by the dashboard 15 and positioned such thatincoming rays of natural light 110 can be reflected from the top surface53 thereof. As earlier discussed, the display face includes amultiplicity of reverse printed translucent characters which are adaptedto reflect the ambient natural light onto the substantially transparentwindscreen 25. The reverse printed characters 60 which constitute afirst portion of the analog display are adapted to produce reflected oremitted light in a predetermined frequency range which is attenuated bythe tint field 41 such that the reflected image appearing in thewindscreen 25 is substantially free of all secondary or "ghost images".

The preferred embodiments of the present invention include apredetermined tint field 41 which is borne by the windscreen 25, andwhich is adapted to selectively absorb the frequencies of light producedby the characters 60 whereby the reflected image of the charactersappear in a predetermined location on the windscreen such that may beobserved within the line of sight of the operator 14. The apparatus 10and 300 further includes an auxiliary lighting assembly 70 and 350 whichis adapted to produce artificial light which is selectively delivered tothe individual translucent characters 60 by way in the first embodiment,of a light manifold 71 which is composed of a plurality of opticalfibers 72. As earlier discussed, and as seen in the second form of theinvention 300, the light manifold may not be necessary in certainapplications. In addition to the foregoing, means are provided forselectively activating the auxiliary lighting assembly 70 and 350 suchthat the individual translucent characters are artificially illuminated.This is accomplished by means of an electronic circuit 79 and 430 whichare individually adapted to selectively actuate the light source 75 andthe light bulbs 364 such that light energy may be transmitted to theindividual characters with the result that they may be viewed inreflection in the predetermined tint field 41, regardless of the levelof ambient natural light present. It should be understood, therefore,that as a vehicle 11 passes in and out of shaded areas, the photosensor95 is adapted to trigger the operation of the electronic circuit 79 and430 such that predetermined amounts of 12 volt power is supplied to thehigh intensity Halogen light source 75 and 364, thus causing lightenergy to be emitted by the translucent characters such that areflection of the individual characters may be seen in the predeterminedtint field regardless of the ambient lighting conditions. During normaldaylight hours, the ambient natural light 110 coming through thewindscreen 25 supplies a large percentage of the light necessary toproduce a reflected image which can be clearly seen in the tint field 41of the windscreen 25.

Electronic circuits 130, 180 and 450, respectively, comprise individualcontrolling means which are operable to convert electrical pulses 131which are produced by the vehicle 11 as a function of its overlandspeed, and convert the electrical pulses into a predetermined voltagewhich varies linearly and inversely relative to the electrical pulserate, or, alternatively, just linearly (400) and which actuates thecoiled spring return meter movement 64 to urge the indicator needle 63to rotate in a proper direction such that a reflection of indicatorneedle 63 appears to move in an appropriate direction when it is viewedfrom the operators position 12.

Therefore, the instrument display apparatus 10 of the present inventionis particularly well suited for use in all manner of overland vehicles,aircraft and watercraft, is adapted to produce a reflected image whichmay be seen under all ambient lighting conditions, which can be mountedon a vehicle as standard equipment or can be produced in the manner of aretrofit, is compact, and easy to assemble and maintain.

Although the invention has been herein shown and described in what isconceived to be the most practical and preferred embodiments, it isrecognized that departures may be made therefrom within the scope of theinvention which is not to be limited to the illustrative detailsdisclosed.

Having described our invention, what we claim as new and desire tosecure by Letters Patent is:
 1. An instrument display apparatus for usein combination with a substantially transparent panel comprising:aninstrument to be displayed having a display face including a firstportion which is translucent and light reflective and a second portionwhich provides contrast for the first portion and wherein the firstportion is adapted to reflect ambient light onto the substantiallytransparent panel; and means for selectively supplying light to saidfirst portion whereby said first portion may be viewed in thesubstantially transparent panel regardless of the level of ambientlight.
 2. An apparatus as claimed in claim 1 wherein said first portiondefines a character, and wherein the first portion produces light inselected frequencies, and wherein an attenuation means is borne by thesubstantially transparent panel and is adapted to absorb the frequenciesof light produced by the first portion whereby the image of the displayface appears on the attenuation means.
 3. An apparatus as claimed inclaim 2 wherein the attenuation means includes a predetermined tintfield, and wherein the first portion includes a translucent character,and the light supplying means includes a light source, a light manifolddisposed in light receiving relation relative to the light source andwhich is adapted to transmit the light onto the character, and a sensorborne by the vehicle and adapted to actuate the light source in theabsence of predetermined levels of ambient light.
 4. An apparatus asclaimed in claim 2 wherein the attenuation means includes apredetermined tint field, and wherein the light supplying means is borneby the vehicle and the display face is positioned between the lightsource and the substantially transparent panel, and wherein the lightsource is adapted to transmit the light onto the character, and whereina sensor is borne by the vehicle and adapted to actuate the light sourcein the absence of predetermined levels of ambient light.
 5. An apparatusas claimed in claim 3 or 4 wherein the tint field includes a syntheticpolymer sheet which is borne by the substantially transparent panel. 6.An apparatus as claimed in claim 3 or 4 wherein the tint field includesa coating applied to the substantially transparent panel.
 7. Anapparatus as claimed in claim 3 or 4 wherein the tint field is madeintegral with the substantially transparent panel.
 8. An apparatus asclaimed in claim 2 wherein the display face is an analog speedometerdisplay which is borne by a vehicle and which includes a plurality ofreverse printed characters, and wherein the instrument further includesa moveable indicator needle, means for driving the needle, and means forselectively controlling the driving means in response to the speed ofmovement of the vehicle.
 9. An apparatus as claimed in claim 8 whereinthe vehicle includes an operator's position, and wherein the vehicleproduces a predetermined number of discreet electrical pulses whichindicates the speed of the vehicle, and wherein the driving meansincludes a coiled spring return meter movement, and wherein thecontrolling means converts the electrical pulses into a predeterminedvoltage which varies linearly and inversely relative to the electricalpulse rate and which actuates the return meter movement to drive theindicator needle in the proper direction when the reflection of theinstrument display is viewed from the operators position.
 10. Anapparatus as claimed in claim 8 wherein the vehicle includes anoperator's position, and wherein the vehicle produces a predeterminednumber of discreet electrical pulses which indicates the speed of thevehicle, and wherein the driving means includes a coiled spring returnmeter movement, and wherein the controlling means converts theelectrical pulses into a predetermined voltage which varies linearlyrelative to the electrical pulse rate and which actuates the returnmeter movement to drive the indicator needle in the proper directionwhen the reflection of the instrument display is viewed from theoperator's position.
 11. An instrument display apparatus comprising:asubstantially transparent panel having a predetermined tint field whichattenuates preselected wavelengths of light; and an instrument to bedisplayed positioned adjacent to the transparent panel and having adisplay face which is adapted to produce light in the selectedwavelengths which are attenuated by the tint field whereby the image ofthe display face appears within the tint field.
 12. An apparatus asclaimed in claim 11 wherein the transparent panel is a windscreen borneby a vehicle and which includes an operator's position and wherein thetint field is located substantially within the line of sight of anoperator who is located in the operator's position whereby the operatormay see the image of the display face while viewing through thewindscreen without substantially diverting his vision.
 13. An apparatusas claimed in claim 11 wherein the instrument display face emits visiblelight with a peak intensity substantially within a predeterminedselected band, and wherein the tint field selectively attenuates thelight emitted from the display face in the predetermined selected band.14. An apparatus as claimed in claim 13 wherein the display faceincludes at least one reverse printed character which is translucent andwhich emits light in the 625-700 nanometer band, and wherein theremainder of the display face surrounding the character providescontrast for the character.
 15. An apparatus as claimed in claim 14wherein the vehicle has a dashboard, and wherein a housing is mounted onthe dashboard and the instrument is supported on the housing and isilluminated by ambient natural light, and wherein a means forartificially illuminating the character is borne by the vehicle and isoperable to provide illumination for the character whereby the image ofthe character appears within the tint field in the absence ofpredetermined levels of ambient natural light.
 16. An apparatus asclaimed in claim 15 wherein the lighting means includes a light sourceborne by the vehicle, and a light manifold is operable selectively tochannel light produced by the light source onto the character.
 17. Anapparatus as claimed in claim 16 wherein the display face has oppositeforwardly and rearwardly facing surfaces, and wherein the light manifoldincludes at least one optical cable having input and output ends, andwherein the output end is mounted on the rearwardly facing surface ofthe display face and channels light onto the character, and wherein theinput end is positioned in light receiving relation relative to thelight source.
 18. An apparatus as claimed in claim 15 wherein thelighting means includes a light source borne by the housing, and whereinthe display face is positioned in light receiving relation relative tothe light source, the display face positioned between the light sourceand the windscreen.
 19. An apparatus as claimed in claim 17 or 18wherein a sensor is borne by the vehicle and is operable selectively toactuate the light source in the absence of predetermined levels ofambient natural light.
 20. An apparatus as claimed in claim 19 whereinthe display face is an analog display.
 21. An apparatus as claimed inclaim 20 wherein the instrument receives a signal from the vehicle, andthe instrument further includes, a movable indicator needle, means fordriving the needle, and means for selectively controlling the movementof the needle in response to the signal received from the vehiclewhereby the image of the indicator needle appearing in the tint fieldappears to move in a proper direction when viewed from the operator'sposition.
 22. An apparatus as claimed in claim 21 wherein the means fordriving the indicator needle includes a coiled spring return metermovement, and wherein the signal received from the vehicle includes apredetermined number of discreet electrical pulses which indicates thevehicle speed and wherein the controlling means is operable to convertthe electrical pulses into a predetermined voltage which varies linearlyrelative to the electrical pulse rate and which actuates the returnmeter movement to drive the indicator needle in the proper directionwhen the reflection of the instrument display is viewed from theoperator's position.
 23. An apparatus as claimed in claim 21 wherein thedisplay face is an analog speedometer display, and wherein the means fordriving the indicator needle includes a coiled spring return metermovement, and wherein the signal received from the vehicle includes apredetermined number of discreet electrical pulses which indicates thevehicle speed, and wherein the controlling means is operable to convertthe electrical pulses into a predetermined voltage which varies linearlyand inversely relative to the electrical pulse rate and which actuatesthe return meter movement to drive the indicator needle in the properdirection when the reflection of the instrument display is viewed fromthe operator's position.
 24. An apparatus as claimed in claim 23 whereinthe vehicle has an electrical power source, and the control meanscomprises:means for regulating voltage electrically connected to thevehicle's electrical power source and having an input, a ground, and anoutput, the voltage regulating means adapted to produce a substantiallyconstant voltage; means for processing the electrical pulses intosubstantially uniform electrical pulses connected to said voltageregulator means and having an input connected to the vehicle forreceiving the electrical pulses, and an output and a ground; anamplifier having an input, an output, and a ground, and wherein theinput of the amplifier is electrically connected to the output of thevoltage regulating means and the output is electrically connected to thereturn meter movement; and means for calibrating the control meanselectrically connected to the amplifier whereby the amplifier suppliesvoltage to the return meter movement which is inversely and linearlyrelated to the vehicle electrical pulse rate.
 25. An apparatus asclaimed in claim 24 wherein the amplifier acts as a low band pass filterand an integrator and wherein the calibrating means includes first andsecond potentiometers, the first potentiometer adapted to regulate theminimum output voltage of the amplifier, and the second potentiometeradapted to regulate the maximum voltage output of the amplifier.
 26. Anapparatus as claimed in claim 25 wherein the voltage regulator means isa 7805 semiconductor chip which is operable to produce a substantiallyconstant 5 volts, and wherein the processing means is a 555semiconductor chip which acts as a monostable to receive the electricalpulses produced by the vehicle and produce a series of pulses having amagnitude of not greater than 5 volts, and a predetermined duration. 27.An apparatus as claimed in claim 26 wherein the amplifier is a 3130semiconductor chip, and wherein the first and second potentiometers arevariable resistors each having a value of 100K ohms.
 28. An apparatus asclaimed in claim 27 wherein the first potentiometer sets a minimumvoltage output for the operational amplifier in a range of approximately0 through 0.3 volts and the second potentiometer sets a maximum voltageoutput for the operational amplifier of approximately 1.4 volts.
 29. Anapparatus as claimed in claim 28 wherein the 3130 semiconductor chipacts as a two pole low band pass filter.
 30. An apparatus as claimed inclaim 24 wherein the amplifier is a noninverting amplifier and whereinthe calibrating means includes a potentiometer which is adapted toregulate the gain and the maximum voltage output of the amplifier. 31.An apparatus as claimed in claim 30 wherein the voltage regulator is aLM317 semiconductor chip which is adjusted to produce a substantiallyconstant voltage and wherein the processing means is a 555 semiconductorchip which acts as a monostable to receive the electrical pulsesproduced by the vehicle and produce a series of pulses having apredetermined magnitude and a predetermined duration.
 32. An apparatusas claimed in claim 31 wherein the amplifier is an operational amplifierand wherein the potentiometer is a variable resistor having a value of100K ohms.
 33. An apparatus as claimed in claim 32 wherein a means forcontrolling current has an input electrically coupled with the output ofthe operational amplifier, and an output which is electrically coupledwith the coiled spring return meter movement, and wherein the currentcontroller means includes a MOSFET "N" Type transistor and a resistorhaving a predetermined value.
 34. An apparatus as claimed in claim 23wherein the vehicle has an electrical power source and the control meanscomprises:means for regulating voltage electrically connected to thevehicle's electrical power source and having an input, a ground, and anoutput, the voltage regulating means adapted to produce a substantiallyconstant voltage; means for modifying the electrical pulses electricallyconnected to the voltage regulating means and with the vehicle and whichis operable to modify the electrical pulses in a manner to formelectrical pulses having a predetermined wave form and amplitude; meansfor processing the electrical pulses into substantially uniformelectrical pulses electrically connected to the voltage regulator means,and having an input electrically connected to the modifier means, and anoutput; means for integrating the electrical pulses and forming anintegrated voltage output, the integrating means electrically connectedwith the output of the processing means; a first amplifier having aninput, and an output, and wherein the input is electrically connectedwith the integrated voltage output of the integrator means, and which isadapted to produce a voltage output which is substantially linearlyrelated to the pulse rate of the vehicle; a second amplifier having aninput, an output, and wherein the input is electrically connected withthe output of the first amplifier, and the output is electricallyconnected to the return meter movement; and means for calibrating thecontrol means electrically connected to the first and second amplifierswhereby the second amplifier supplies a predetermined voltage to thereturn meter movement which is inversely and linearly related to thevehicle's electrical pulse rate.
 35. An apparatus as claimed in claim 34wherein the voltage regulator means includes a 7805 IC which is adaptedto produce a substantially constant 5 volts, and wherein the modifiermeans includes a pair of diodes and a resistor having predeterminedvalues and which are adapted to produce modified electrical pulseshaving the predetermined wave form, and wherein the amplitude of themodified electrical pulses are not greater than 5 volts.
 36. Anapparatus as claimed in claim 35 wherein the processing means includes a555 IC which acts as a monostable and which produces electrical pulseshaving a magnitude of not greater than 5 volts and a predeterminedduration, and wherein the integrating means includes a resistor and acapacitor having values of 100K ohms and 2.2 microfarads, respectively.37. An apparatus as claimed in claim 36 wherein the first and secondamplifiers are operational amplifiers which are made integral with anLM324 quad-operational amplifier, and wherein the calibration meansincludes first and second variable resistors having values of 100K ohms,respectively.
 38. An apparatus as claimed in claim 37 wherein the firstvariable resistor sets the maximum voltage output for the secondamplifier in a range of approximately 1.4 volts and the second variableresistor sets the minimum voltage output for the second amplifier ofapproximately 0 through 0.3 volts.
 39. An apparatus as claimed in claim34 wherein the voltage regulator means includes a LM317 semiconductorchip which is adapted to produce a substantially constant voltage andwherein the modifier means includes a pair of diodes and a resistorhaving predetermined values and which are adapted to produce modifiedelectrical pulses having the predetermined wave form and wherein theamplitude of the modified electrical pulses is not greater than thevoltage output value of the LM317.
 40. An apparatus as claimed in claim39 wherein the processing means includes a 555 IC which acts as amonostable and which produces electrical pulses having a magnitude notgreater than the voltage output produced by the LM317 and apredetermined duration, and wherein the integrating means includes aresistor and a capacitor having values of 100K ohms and 2.2 microfarads,respectively.
 41. An apparatus as claimed in claim 40 and wherein thefirst and second amplifiers are operational amplifiers which are madeintegral with an LM324 quad operational amplifier and wherein thecalibration means includes first and second variable resistors havingvalues of 100K ohms, respectively.
 42. An apparatus as claimed in claim41 wherein the first variable resistor sets the maximum voltage outputfor the second amplifier in a range of approximately 7.5 volts and thesecond variable resistor sets the minimum voltage for the secondamplifier of approximately 0 through 0.3 volts.
 43. An apparatus asclaimed in claim 34 and wherein a means for controlling current iselectrically connected to the second operational amplifier and with thecoiled spring return meter movement, and wherein the current controllermeans includes a MOSFET "N" Type transistor which provides apredetermined output voltage to the coiled spring return meter movement.44. An apparatus as claimed in claim 11 wherein the tint field includesa synthetic polymer sheet secured on the substantially transparentpanel.
 45. An apparatus as claimed in claim 11 wherein the tint fieldincludes a coating applied on the inside surface of the transparentpanel.
 46. An apparatus as claimed in claim 11 wherein the tint field ismade integral with the transparent panel.
 47. An instrument displayapparatus for a vehicle having an operator's position, a dashboard, anda windscreen mounted adjacent to the dashboard, the apparatuscomprising:a housing fixed on the dashboard; an instrument mounted onthe housing and positioned adjacent to the windscreen, the instrumenthaving a display face including at least one character which reflectsambient natural light at selected frequencies; a predetermined tintfield borne by the windscreen and positioned in adjacent space relationrelative to the display face, the tint field adapted to absorb thefrequencies of light reflected by the character; and means forselectively illuminating the character in the absence of predeterminedlevels of ambient natural light, said illuminating means borne by thehousing and causing said character to emit light in the frequenciesabsorbed by the tint field, and wherein a reflection of the characterappears in the tint field such that it may be viewed from the operator'sposition as an operator looks through the windscreen.
 48. An apparatusas claimed in claim 47 wherein the display face is an analog speedometerdisplay having a movable indicator needle, and wherein the analogspeedometer display has a multiplicity of reverse printed, translucentcharacters which emit light in the frequencies absorbed by the tintfield, and wherein the remainder of the analog speedometer display facesurrounding the characters provides contrast for the individualcharacters.
 49. An apparatus as claimed in claim 48 wherein theindividual characters emit light with a peak intensity in apredetermined frequency band, and wherein the illuminating meansincludes a light source which is borne by the housing, and wherein thelight source delivers the light onto the individual characters, andwherein means are provided for selectively actuating said light sourcein the absence of predetermined levels of ambient natural light.
 50. Anapparatus as claimed in claim 49 wherein a coiled spring return metermovement is borne by the housing and is operable selectively to move theindicator needle to predetermined indicating positions along the displayface, and wherein the vehicle produces a predetermined number ofelectrical pulses which indicates the speed of the vehicle, and whereinan electric circuit means is borne by the vehicle and is adapted toreceive and process the electrical pulses into a source of voltage foractuating the meter movement which varies linearly and inverselyrelative to the rate of electrical pulsing.
 51. An apparatus as claimedin claim 50 and wherein the source of voltage for activating the metermovement varies linearly relative to the rate of electrical pulsing. 52.An apparatus as claimed in claim 50 wherein the electric circuit meanscomprises:a source of voltage borne by the vehicle; a voltage regulatorconnected with the source of voltage and producing a substantiallyconstant voltage output; a monostable semiconductor chip connected inelectrical pulse receiving relationship relative to the vehicle and involtage receiving relation relative to the voltage regulator, themonostable semiconductor chip producing substantially uniform electricalpulses having a substantially uniform amplitude and a predeterminedduration; an amplifier disposed in electrical pulse receivingrelationship relative to the monostable semiconductor chip and involtage transmitting relation relative to the return meter movement, theoperational amplifier producing an output voltage which varies linearlyrelative to the electrical pulse rate; and means for calibrating theoutput voltage of the amplifier whereby the return meter movement isoperable to move the indicator needle to selective locations along thedisplay face which correctly indicates the overland speed of thevehicle.
 53. An apparatus as claimed in claim 52 wherein the voltageregulator is a 7805 semiconductor chip and the monostable semiconductorchip is a 555 semiconductor chip.
 54. An apparatus as claimed in claim53 wherein the amplifier is a 3130 semiconductor chip and thecalibration means includes first and second potentiometers which areindividually operable to adjust the minimum and maximum voltage outputof the 3130 semiconductor chip, and wherein the operational amplifierproduces an output voltage which varies linearly and inversely relativeto the electrical pulse rate.
 55. An apparatus as claimed in claim 54wherein the first and second potentiometers are variable resistorshaving individual resistance values of substantially 100K ohms.
 56. Anapparatus as claimed in claim 52 wherein the voltage regulator is aLM317 semiconductor chip and the monostable conductor chip is a 555semiconductor chip.
 57. An apparatus as claimed in claim 56 wherein theamplifier is an operational amplifier borne by an LM324 semiconductorchip and the calibration means includes a potentiometer which isindividually operable to adjust the gain and maximum voltage output ofthe operational amplifier.
 58. An apparatus as claimed in claim 57 andwherein a means for controlling current is electrically connected to theoperational amplifier and with the coiled spring return meter movement,and wherein the current control means includes an "N" type MOSFETtransistor.
 59. An apparatus as claimed in claim 50 wherein theelectrical circuit means comprises:a source of voltage borne by thevehicle; a voltage regulator connected with the source of voltage andproducing a substantially constant voltage; a means for modifying theelectrical pulses produced by the vehicle, said modifying meanselectrically connected with the vehicle and with the voltage regulator;a monostable semiconductor chip connected in electrical pulse receivingrelationship relative to the modifier means and with the voltageregulator, the monostable semiconductor chip producing electrical pulseshaving a substantially uniform amplitude and a predetermined duration;means for integrating the electrical pulses produced by the monostablesemiconductor chip and producing an integrated output voltage; a firstoperational amplifier disposed in voltage receiving relationshiprelative to the integrating means, the first operational amplifierproducing a voltage output which varies substantially linearly relativeto the pulse rate of the vehicle; a second operational amplifierdisposed in voltage receiving relationship relative to the firstoperational amplifier and in voltage transmitting relationship relativeto the return meter movement, the second operational amplifier producinga substantially continuous voltage output which varies linearly andinversely relative to the electrical pulse rate of the vehicle; andmeans for calibrating the output voltage of the second operationalamplifier whereby the return meter movement is operable to move theindicator needle to a selective location along the display face whichcorrectly indicates the overland speed of the vehicle.
 60. An apparatusas claimed in claim 59 wherein the modifier means includes a resistorand a pair of diodes having predetermined values and which are operableto modify the electrical pulses to form pulses having predetermined waveforms and amplitudes.
 61. An apparatus as claimed in claim 60 whereinthe monostable semiconductor chip is a 555 IC and the first and secondoperational amplifiers are made integral with an LM324 quad operationalamplifier, and wherein the calibrating means includes first and secondpotentiometers which are individually operable to adjust the maximum andminimum voltage output of the second operational amplifier.
 62. Anapparatus as claimed in claim 61 wherein the first and secondpotentiometers are variable resistors having individual resistancevalues of substantially 100K ohms.
 63. An apparatus as claimed in claim59 wherein the means for selectively actuating the light source is madeintegral with the electronic circuit means, the light source actuatingmeans comprising:a potentiometer borne by the vehicle and electricallyconnected with the source of voltage; a voltage regulator electricallyconnected with the source of voltage borne by the vehicle and having aninput electrically connected with the potentiometer and an outputelectrically connected with the light source; and a photosensor and aresistor electrically connected with the output of the voltage regulatorwhereby the output voltage of the voltage regulator is proportional tothe resistance of the potentiometer and inversely proportional to thesum of the resistance of the photosensor and the resistor.
 64. Anapparatus as claimed in claim 63 wherein a capacitor is electricallyconnected between the resistor, the photosensor and ground and which isadapted to act as a filter.
 65. An apparatus as claimed in claim 59wherein the electronic circuit includes means for controlling currentwhich is electrically coupled to the output of the second operationalamplifier and with coiled spring return meter movement, and wherein thecurrent controller means includes an "N" type MOSFET transistor.
 66. Anapparatus as claimed in claim 59 wherein the electronic circuit meansincludes the means for selectively actuating the light source, the lightsource actuating means comprising:a source of voltage borne by thevehicle; a switch electrically coupled to the source of voltage andhaving an open and closed position; a voltage regulator having an inputand an output and wherein the input of the voltage regulator iselectrically coupled with the switch; a photosensor electrically coupledwith the output of the voltage regulator; a first resistor coupled inparallel with the photosensor; a second resistor coupled in series withthe first resistor and with the photosensor; a potentiometerelectrically coupled with the second resistor and ground; and at leastone light bulb electrically coupled to the output of the voltageregulator and wherein when the switch is in the closed position thevoltage regulator produces an output voltage which is proportional tothe resistance of the potentiometer and inversely related to theresistances of the photosensor and the first and second resistors. 67.An apparatus as claimed in claim 49 wherein the light actuating meanscomprises:a source of voltage borne by the vehicle; a potentiometerelectrically connected with the source of voltage; a switch electricallyconnected with the potentiometer; a voltage regulator having an inputelectrically connected with the switch and potentiometer, and an outputelectrically connected with the light source; and a photosensor and aresistor electrically connected with the output of the voltage regulatorwhereby the output voltage of the voltage regulator is proportional tothe resistance of the potentiometer and inversely proportional to thesum of the resistance of the photosensor and the resistor.
 68. Anapparatus as claimed in claim 67 wherein a capacitor is electricallyconnected between the resistor, the photosensor, and ground, and isoperable to act as a filter.
 69. An apparatus as claimed in claim 49wherein the light actuating means comprises:a source of voltage borne bythe vehicle; a switch electrically coupled to the source of voltage andhaving an open and closed positions; a voltage regulator having an inputand an output and wherein the input of the voltage regulator iselectrically coupled with the switch; a photosensor electrically coupledwith the output of the voltage regulator; a first resistor coupled inparallel with the photosensor; a second resistor coupled in series withthe first resistor and with the photosensor; a potentiometerelectrically coupled with the second resistor and ground; and a lightsource electrically coupled to the output of the voltage regulator andwherein when the switch is in the closed position the voltage regulatorproduces an output voltage which is proportional to the resistance ofthe potentiometer, and inversely related to the resistance of thephotosensor.
 70. An apparatus as claimed in claim 69 and wherein acapacitor is electrically coupled to the voltage regulator and isoperable to act as a filter.